Misbelieving you’ve got sleep problems can be more harmful than actual lack of sleep

"In the dark, in the quiet, in the lonely stillness, the aggrieved struggle to rescue sleep from vigilance." This arresting sentence introduces a new review of insomnia in Behaviour Research and Therapy that addresses a troubling fact observed in sleep labs across the world: poor sleep is not sufficient to make people consider themselves to have the condition… and poor sleep may not even be necessary. The paper, by Kenneth Lichstein at the University of Alabama, explores the implications of "Insomnia Identity": how it contributes to health problems, and may be an obstacle to recovery.

The hallmark of insomnia is regularly having such poor sleep that it affects your daily function. This implies a person with insomnia will have poor sleep, as measured objectively, and that they will complain about their lack of sleep. To get a sense of how poor sleep and reports of insomnia interact, Lichstein reviewed twenty studies that measured each of these aspects separately, with questions like "How long does it typically take you to get to sleep?" on the one hand, and on the other, questions like "Are you dissatisfied with your sleep?" or direct probes into how confident the person was that they struggled with insomnia.

The evidence shows that poor sleep in itself is not sufficient to produce insomnia. A 1995 study looked at 400 community volunteers (age 55 or more), and found that the majority of people who were technically poor sleepers (in this case, six months where it took 30 minutes or more of struggle to fall asleep on at least three nights per week) did not experience distress or consider themselves to have insomnia. These "non-complaining poor sleepers" were no more impaired in terms of daily fatigue than those who got good sleep, nor did they have high anxiety.

Studies using polysomnography (which involves brain wave recordings and other physiological measures of sleep state) and sleep diaries – both considered more accurate ways of establishing quality of sleep than simple recall – have reinforced these findings. One replication also showed non-complaining sleepers had levels of anxiety and depression no higher than the general population. And a large data set of 1700 participants found that whereas short sleep was associated with a 350-500 per cent increase in hypertension (correlated with severity of sleep deficit), this wasn't the case for people who didn't consider themselves to have insomnia, for whom there was no relationship between sleep duration and blood pressure. So poor sleep doesn't inevitably cause the experience of insomnia, nor produce the knock-on health effects associated with insomnia.

On the other hand, poor sleep isn't necessary for people to complain that they have insomnia. Polysomnography and sleep diary studies show clearly that people whose sleeping patterns do not meet clinical criteria for poor sleep can nonetheless believe that they suffer insomnia. What's more, these "complaining good sleepers" can have as high impairment in terms of daily fatigue, anxiety and depression as those suffering under a clinical deficit of sleep. Recent work suggests that quality of the sleep you experience has, in itself, no relationship to suicidal thoughts. Suicidal thoughts are instead, related to whether you feel you have sleep problems, regardless of whether or not you do.

Summing across the major studies that separate out sleep quality from insomnia complaint, Lichtstein reports that 37 per cent of individuals complaining of insomnia "do not have poor sleep by conventional standards". This is not to say that their sleep was flawless, or that it wasn't worse than average in some way, but it certainly falls in the normal range. On the other hand, many individuals with non-normal levels of sleep problems are able to exist as if free from insomnia. What is going on?

Lichstein suggests that good sleepers who see themselves as insomniac have a kind of "insomnia identity" driven by biases in the way they think about their sleep (consistent with this, Cognitive Behavioural Therapy/CBT, which addresses such biases, is an effective intervention for insomnia) For instance, individuals with an insomnia identity may have acquired unrealistic expectations, seeing a 15 minute period of wakefulness before dropping off as aberrant. Temperaments drawn to hypochondria, or liable to catastrophic thinking (believed to contribute to some chronic pain conditions) may symptomise minor events or exaggerate their implications. If symptoms are in remission, insomniacs may be hypervigilant for even a single night's poor sleep as evidence that "it's back". Such anxieties make sleep harder, and also colour the edges of sleeping existence with the dread that Lichstein alludes to in his opening sentence. In principle, bed-time can become a living hell even if the actual sleeping difficulties are not remarkable, or scarcely different from a poor sleeper who doesn't attend to it as an issue.

It may be especially difficult for therapists to help people with an insomnia identity – even when a therapist succeeds in helping such a client improve their sleep, it's likely their belief they have a problem will endure. Research on insomnia stigma suggests that it's common for sufferers to have their problem doubted: this could produce perverse incentives for hypervigilance among those with an insomnia identity and a resolute sense that their problem is real and severe.

As the diagnosis of insomnia usually begins with a person's complaint about their sleep, and most medical practices offer at most a token sleep assessment before providing that diagnosis, there may be many people out there suffering because of their insomnia identity rather than an actual lack of sleep. Lichtstein recommends that in addition to CBT, we explore practices like mindfulness and dialectical practices that get the sufferer to question assumptions through questions like: what is normal sleep? Does sleep need to be perfect? Do I need to see myself as an insomniac? In these ways, psychology can conquer an affliction that keeps many in unnecessary misery.